Quietly, the man occupies young relative (6)
I believe the answer is:
nephew
'relative' is the definition.
(type of relative)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for nephew that I've seen before include "Brother's/sister's son" , "Has a duty (to do something)" , "A sibling's child" , "Male relative" , "Sister's son" .)